Epidemiologic evidence supports an association between particulate air pollution and cardiovascular morbidity and mortality, however biological mechanisms for this relationship have not yet been elucidated. Recent research suggests that inflammatory markers are feasible indicators of cardiovascular outcomes and that exposure to particulate air pollution may elevate certain inflammatory markers. Using data from nested case-control studies of coronary heart disease (CHD) embedded in the Nurses' Health Study and the Health Professionals' Follow-up Study, we propose to examine the relationships among chronic particulate exposure, inflammatory markers and CHD. To obtain more accurate estimates of particulate exposure, a complex Geographic Information System (CIS) model will be applied. We will also use Structural Equation Models (SEM) to examine the complex interrelationships among particulate exposure, inflammatory markers and CHD. Hypothesis 1: Chronic particulate exposure increases inflammatory markers related to CHD. Specific Aims: Examine the association between inflammatory markers and chronic exposure to PM2.5 and PM10. Hypothesis 2: Chronic particulate exposure increases the risk of CHD. Specific Aims: Assess whether particulate exposures are elevated among persons with CHD and whether inflammatory markers modify the relationship between particulate exposure and CHD. Hypothesis 3: Inflammatory markers mediate the relationship between CHD and chronic particulate exposure. Specific Aims: Use SEM to examine the direct and indirect contribution of particulate exposure to CHD. [unreadable] [unreadable]